 |
| Titel |
Gross community production and metabolic balance in the South Pacific Gyre, using a non intrusive bio-optical method |
| VerfasserIn |
H. Claustre, Y. Huot, I. Obernosterer, B. Gentili, D. Tailliez, M. Lewis |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 5, no. 2 ; Nr. 5, no. 2 (2008-03-28), S.463-474 |
| Datensatznummer |
250002378
|
| Publikation (Nr.) |
 copernicus.org/bg-5-463-2008.pdf |
|
|
|
|
|
| Zusammenfassung |
| The very clear waters of the South Pacific Gyre likely constitute an
end-member of oligotrophic conditions which remain essentially unknown with
respect to its impact on carbon fixation and exportation. We describe a
non-intrusive bio-optical method to quantify the various terms of a
production budget (Gross community production, community losses, net
community production) in this area. This method is based on the analysis of
the diel cycle in Particulate Organic Carbon (POC), derived from high
frequency measurements of the particle attenuation coefficient cp. We
report very high integrated rates of Gross Community Production within the
euphotic layer (average of 846±484 mg C m−2 d−1 for 17 stations) that are far above any rates determined using incubation
techniques for such areas. Furthermore we show that the daily production of
POC is essentially balanced by the losses so that the system cannot be
considered as net heterotrophic. Our results thus agree well with
geochemical methods, but not with incubation studies based on oxygen
methods. We stress to the important role of deep layers, below the euphotic
layer, in contributing to carbon fixation when incident irradiance at the
ocean surface is high (absence of cloud coverage). These deep layers, not
considered up to know, might fuel part of the heterotrophic processes in the
upper layer, including through dissolved organic carbon. We further
demonstrate that, in these extremely clear and stratified waters, integrated
gross community production is proportional to the POC content and surface
irradiance via an efficiency index ψ GCP*, the water
column cross section for Gross Community Production. We finally discuss our
results in the context of the role of oligotrophic gyre in the global carbon
budget and of the possibility of using optical proxies from space for the
development of growth community rather than primary production global
models. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|